For question 19, I believe you are asking 3/8 ____ 3 /(3/5).
The first step in comparing fractions is to get a common denominator. Then you will only need to compare the numerators.
We will start with the term on the right, 3/(3/5)
The first thing you need to do is to eliminate the fraction in the denominator. To do this you need to multiple by the recipricol of 3/5 which is 5/3. If you are multiplying the denominator by 5/3 you also need to mulriply the numerator by 5/3. So you would multiply (3x(5/3) )/ ((3/5)x(5/3)). The result is (15/3)/1 or 15/3 = 5
Your comparison is now 3/8 ____ 5. It can be seen that 3/8 is less than 5, without having to convert 5 to a fraction, but to compare both in fractions they would be 3/8 ___ 40/8. the 3 is less than 40, so you would need to use the < sign.
Your correct answer is 3/8 < 3/(3/5)
For question 20, to add fractions use need a common denominator. You have been asked to add -3/8 + -4/8. You already have a common denominator of 8, so you need to add the numerators. -3 + -4 = -7
-3/8 + -4/8 = -7/8. To reduce to simplest term you need to determine if the numerator & denominator have any common factors. In this case, -7 and 8 have no common factors, so -7/8 is already in simplest terms.
I hope this explanation helps you with other problems in the future.